Importance: Hospitals and health care systems face increasing accountability for postdischarge outcomes of patients, but it is unclear how frequently hospital readmissions in particular occur at a different hospital than the index hospitalization and whether this is associated with worse outcomes.
Objective: Describe the prevalence of nonindex 30-day readmissions in a nationally representative sample of all payers and associations with outcomes.
Design: Secondary retrospective analysis of the 2013 Nationwide Readmissions Database.
Setting: Nonfederal hospitals from 21 states representing half of hospitalizations in the United States annually.
Participants: Our overall sample included all adults discharged alive from an inpatient stay with 30 days of follow-up; we also created 3 additional cohorts: patients with Medicare as the payer (Medicare cohort), patients discharged to home health or skilled nursing facilities after discharge (postacute care cohort), and Medicare patients with any of the current Hospital Readmission Reduction Program's penalized conditions (readmission penalty cohort).
Exposure: Readmission within 30 days to "index" hospital (where index stay occurred) or "nonindex" hospital.
Main outcome(s) and measure(s): In-hospital mortality and length of stay during the readmission.
Results: The weighted overall sample included 22,884,505 hospital discharges from 2004 unique hospitals. The overall 30-day readmission rate was 11.9%, of these, 22.5% occurred at a nonindex hospital. Readmissions to nonindex facilities were associated with increased odds of in-hospital mortality (odds ratio, 1.21; 95% confidence interval, 1.17-1.25) and longer hospital length of stay (hazard ratio for hospital discharge, 0.87; 95% confidence interval, 0.86-0.88) in the overall sample and in the 3 cohorts.
Conclusions and relevance: Nonindex readmissions are common and associated with worse outcomes; the common findings across cohorts highlight the importance for hospitals and care systems participating in value-based payment models. Hospitals and care systems should invest in improved methods for real-time identification and intervention for these patients.